/*
 * ====================================================================
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 *
 */

package com.feilong.lib.org.apache.http.util;

import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;
import java.io.UnsupportedEncodingException;
import java.nio.charset.Charset;
import java.nio.charset.UnsupportedCharsetException;

import com.feilong.lib.org.apache.http.HttpEntity;
import com.feilong.lib.org.apache.http.HttpResponse;
import com.feilong.lib.org.apache.http.ParseException;
import com.feilong.lib.org.apache.http.entity.ContentType;
import com.feilong.lib.org.apache.http.protocol.HTTP;

/**
 * Static helpers for dealing with {@link HttpEntity}s.
 *
 * @since 4.0
 */
public final class EntityUtils{

    private static final int DEFAULT_BUFFER_SIZE = 4096;

    private EntityUtils(){
    }

    /**
     * Ensures that the entity content is fully consumed and the content stream, if exists,
     * is closed. The process is done, <i>quietly</i> , without throwing any IOException.
     *
     * @param entity
     *            the entity to consume.
     *
     *
     * @since 4.2
     */
    public static void consumeQuietly(final HttpEntity entity){
        try{
            consume(entity);
        }catch (final IOException ignore){}
    }

    /**
     * Ensures that the entity content is fully consumed and the content stream, if exists,
     * is closed.
     *
     * @param entity
     *            the entity to consume.
     * @throws IOException
     *             if an error occurs reading the input stream
     *
     * @since 4.1
     */
    public static void consume(final HttpEntity entity) throws IOException{
        if (entity == null){
            return;
        }
        if (entity.isStreaming()){
            final InputStream inStream = entity.getContent();
            if (inStream != null){
                inStream.close();
            }
        }
    }

    //---------------------------------------------------------------

    /**
     * Updates an entity in a response by first consuming an existing entity, then setting the new one.
     *
     * @param response
     *            the response with an entity to update; must not be null.
     * @param entity
     *            the entity to set in the response.
     * @throws IOException
     *             if an error occurs while reading the input stream on the existing
     *             entity.
     * @throws IllegalArgumentException
     *             if response is null.
     *
     * @since 4.3
     */
    public static void updateEntity(final HttpResponse response,final HttpEntity entity) throws IOException{
        Args.notNull(response, "Response");
        consume(response.getEntity());
        response.setEntity(entity);
    }

    /**
     * Read the contents of an entity and return it as a byte array.
     *
     * @param entity
     *            the entity to read from=
     * @return byte array containing the entity content. May be null if
     *         {@link HttpEntity#getContent()} is null.
     * @throws IOException
     *             if an error occurs reading the input stream
     * @throws IllegalArgumentException
     *             if entity is null or if content length &gt; Integer.MAX_VALUE
     */
    public static byte[] toByteArray(final HttpEntity entity) throws IOException{
        Args.notNull(entity, "Entity");
        final InputStream inStream = entity.getContent();
        if (inStream == null){
            return null;
        }
        try{
            Args.check(entity.getContentLength() <= Integer.MAX_VALUE, "HTTP entity too large to be buffered in memory");
            int capacity = (int) entity.getContentLength();
            if (capacity < 0){
                capacity = DEFAULT_BUFFER_SIZE;
            }
            final ByteArrayBuffer buffer = new ByteArrayBuffer(capacity);
            final byte[] tmp = new byte[DEFAULT_BUFFER_SIZE];
            int l;
            while ((l = inStream.read(tmp)) != -1){
                buffer.append(tmp, 0, l);
            }
            return buffer.toByteArray();
        }finally{
            inStream.close();
        }
    }

    private static String toString(final HttpEntity entity,final ContentType contentType) throws IOException{
        final InputStream inStream = entity.getContent();
        if (inStream == null){
            return null;
        }
        try{
            Args.check(entity.getContentLength() <= Integer.MAX_VALUE, "HTTP entity too large to be buffered in memory");
            int capacity = (int) entity.getContentLength();
            if (capacity < 0){
                capacity = DEFAULT_BUFFER_SIZE;
            }
            Charset charset = null;
            if (contentType != null){
                charset = contentType.getCharset();
                if (charset == null){
                    final ContentType defaultContentType = ContentType.getByMimeType(contentType.getMimeType());
                    charset = defaultContentType != null ? defaultContentType.getCharset() : null;
                }
            }
            if (charset == null){
                charset = HTTP.DEF_CONTENT_CHARSET;
            }
            final Reader reader = new InputStreamReader(inStream, charset);
            final CharArrayBuffer buffer = new CharArrayBuffer(capacity);
            final char[] tmp = new char[1024];
            int l;
            while ((l = reader.read(tmp)) != -1){
                buffer.append(tmp, 0, l);
            }
            return buffer.toString();
        }finally{
            inStream.close();
        }
    }

    /**
     * Get the entity content as a String, using the provided default character set
     * if none is found in the entity.
     * If defaultCharset is null, the default "ISO-8859-1" is used.
     *
     * @param entity
     *            must not be null
     * @param defaultCharset
     *            character set to be applied if none found in the entity,
     *            or if the entity provided charset is invalid or not available.
     * @return the entity content as a String. May be null if
     *         {@link HttpEntity#getContent()} is null.
     * @throws ParseException
     *             if header elements cannot be parsed
     * @throws IllegalArgumentException
     *             if entity is null or if content length &gt; Integer.MAX_VALUE
     * @throws IOException
     *             if an error occurs reading the input stream
     * @throws java.nio.charset.UnsupportedCharsetException
     *             Thrown when the named entity's charset is not available in
     *             this instance of the Java virtual machine and no defaultCharset is provided.
     */
    public static String toString(final HttpEntity entity,final Charset defaultCharset) throws IOException,ParseException{
        Args.notNull(entity, "Entity");
        ContentType contentType = null;
        try{
            contentType = ContentType.get(entity);
        }catch (final UnsupportedCharsetException ex){
            if (defaultCharset == null){
                throw new UnsupportedEncodingException(ex.getMessage());
            }
        }
        if (contentType != null){
            if (contentType.getCharset() == null){
                contentType = contentType.withCharset(defaultCharset);
            }
        }else{
            contentType = ContentType.DEFAULT_TEXT.withCharset(defaultCharset);
        }
        return toString(entity, contentType);
    }

    /**
     * Get the entity content as a String, using the provided default character set
     * if none is found in the entity.
     * If defaultCharset is null, the default "ISO-8859-1" is used.
     *
     * @param entity
     *            must not be null
     * @param defaultCharset
     *            character set to be applied if none found in the entity
     * @return the entity content as a String. May be null if
     *         {@link HttpEntity#getContent()} is null.
     * @throws ParseException
     *             if header elements cannot be parsed
     * @throws IllegalArgumentException
     *             if entity is null or if content length &gt; Integer.MAX_VALUE
     * @throws IOException
     *             if an error occurs reading the input stream
     * @throws java.nio.charset.UnsupportedCharsetException
     *             Thrown when the named charset is not available in
     *             this instance of the Java virtual machine
     */
    public static String toString(final HttpEntity entity,final String defaultCharset) throws IOException,ParseException{
        return toString(entity, defaultCharset != null ? Charset.forName(defaultCharset) : null);
    }

    /**
     * Read the contents of an entity and return it as a String.
     * The content is converted using the character set from the entity (if any),
     * failing that, "ISO-8859-1" is used.
     *
     * @param entity
     *            the entity to convert to a string; must not be null
     * @return String containing the content.
     * @throws ParseException
     *             if header elements cannot be parsed
     * @throws IllegalArgumentException
     *             if entity is null or if content length &gt; Integer.MAX_VALUE
     * @throws IOException
     *             if an error occurs reading the input stream
     * @throws java.nio.charset.UnsupportedCharsetException
     *             Thrown when the named charset is not available in
     *             this instance of the Java virtual machine
     */
    public static String toString(final HttpEntity entity) throws IOException,ParseException{
        Args.notNull(entity, "Entity");
        return toString(entity, ContentType.get(entity));
    }

    //    /**
    //     * Obtains character set of the entity, if known.
    //     *
    //     * @param entity
    //     *            must not be null
    //     * @return the character set, or null if not found
    //     * @throws ParseException
    //     *             if header elements cannot be parsed
    //     * @throws IllegalArgumentException
    //     *             if entity is null
    //     *
    //     * @deprecated (4.1.3) use {@link ContentType#getOrDefault(HttpEntity)}
    //     */
    //    @Deprecated
    //    public static String getContentCharSet(final HttpEntity entity) throws ParseException{
    //        Args.notNull(entity, "Entity");
    //        String charset = null;
    //        if (entity.getContentType() != null){
    //            final HeaderElement values[] = entity.getContentType().getElements();
    //            if (values.length > 0){
    //                final NameValuePair param = values[0].getParameterByName("charset");
    //                if (param != null){
    //                    charset = param.getValue();
    //                }
    //            }
    //        }
    //        return charset;
    //    }

    //    /**
    //     * Obtains MIME type of the entity, if known.
    //     *
    //     * @param entity
    //     *            must not be null
    //     * @return the character set, or null if not found
    //     * @throws ParseException
    //     *             if header elements cannot be parsed
    //     * @throws IllegalArgumentException
    //     *             if entity is null
    //     *
    //     * @since 4.1
    //     *
    //     * @deprecated (4.1.3) use {@link ContentType#getOrDefault(HttpEntity)}
    //     */
    //    @Deprecated
    //    public static String getContentMimeType(final HttpEntity entity) throws ParseException{
    //        Args.notNull(entity, "Entity");
    //        String mimeType = null;
    //        if (entity.getContentType() != null){
    //            final HeaderElement values[] = entity.getContentType().getElements();
    //            if (values.length > 0){
    //                mimeType = values[0].getName();
    //            }
    //        }
    //        return mimeType;
    //    }

}
